Blood for Armok, god of blood. So now we can get a DF, WH, and DoomRL reference all rolled up into one. o3o
Armok and Kek are the only true gods. Blood for Armok and memes (and repeating digits) for Kek.
I've done quite a few things myself that I felt remorse for. The first really awful moment for me was one I've posted before - during a bandit raid on a village, I killed all of them except for a human hammerwoman. I proceeded to break all the joints in her body, and mangled her face (punching out her teeth, gouging out her eyes, cutting off her ears and biting off her tongue). Then I ripped off all her clothes and threw them back at her (which ended up breaking the bone in one of her hands, somehow).
I left her crawling for a few seconds before I mercy-killed her.
Another moment, I was a spearman going after a minotaur. I found it's labyrinth, and after a build-up of it constantly threatening me, when I finally came across it went "I must withdraw" and ran straight into a corner - I then stabbed it, which broke some bones and knocked it out - what made it feel even worse is that I tried to go for a quick mercy kill by stabbing it in the head with my spear, but it took like 5 stabs before it tore the brain. I imagined the minotaur just sitting in a fetal position going "oh Armok, what do they want? What the hell do they want?" after it realized that threats didn't scare my group off.
After I started modding, I once fought a chimera as a centaur - it tore my upper spine's nervous tissue with it's stinger, which left me crawling around the ground. At that point I started biting, since I knew I was going to die anyway - a bite to the paw knocked it out, at which point I started biting off all of the chimera's toes, and also all of it's heads ears, tongues, and eyes. It didn't die, but I suffocated.
When I went there later, the thing was mangled and completely blinded, so it wouldn't react even when I was beating on it. I imagine it acting like a really traumatized dog or something, letting everything happen. Just with wings, a stinger, and 3 different heads. Felt pretty bad. Not quite as bad as the previous two stories, considering the chimera actually killed me once, but eh.
Lastly, I got attacked by a murloc child, as I killed his father in front of him (to my defense, I was just following orders - my military commander gave me a quest to kill a murloc who was the mayor of a hamlet) - what made it bad for me is that I went a bit overboard with finishing the child off - I spilled his guts, then punched them, giving the "injured part is smashed into the body, an unrecognizable mass", after which I severed them.
I'm guessing the sequence of events was something like a Mortal Kombat fatality - I spilled the guts, punched them back inside the body, making them come out of the murlocs mouth in a pulped form, then I severed them as they were hanging there.